scholarly journals Titanium Dioxide as a Catalyst Support in Heterogeneous Catalysis

2014 ◽  
Vol 2014 ◽  
pp. 1-21 ◽  
Author(s):  
Samira Bagheri ◽  
Nurhidayatullaili Muhd Julkapli ◽  
Sharifah Bee Abd Hamid
Keyword(s):  
Active Sites ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Supported Metal Catalysts ◽  
Support Material ◽  
Oxidation Reactions ◽  
Base Property ◽  
Metal Support Interaction

The lack of stability is a challenge for most heterogeneous catalysts. During operations, the agglomeration of particles may block the active sites of the catalyst, which is believed to contribute to its instability. Recently, titanium oxide (TiO2) was introduced as an alternative support material for heterogeneous catalyst due to the effect of its high surface area stabilizing the catalysts in its mesoporous structure. TiO2supported metal catalysts have attracted interest due to TiO2nanoparticles high activity for various reduction and oxidation reactions at low pressures and temperatures. Furthermore, TiO2was found to be a good metal oxide catalyst support due to the strong metal support interaction, chemical stability, and acid-base property. The aforementioned properties make heterogeneous TiO2supported catalysts show a high potential in photocatalyst-related applications, electrodes for wet solar cells, synthesis of fine chemicals, and others. This review focuses on TiO2as a support material for heterogeneous catalysts and its potential applications.

scholarly journals Homochiral metal–organic frameworks as heterogeneous catalysts

2018 ◽  
Vol 5 (7) ◽  
pp. 1512-1523 ◽  
Author(s):  
Andreea Gheorghe ◽  
Martijn A. Tepaske ◽  
Stefania Tanase
Keyword(s):  
Surface Area ◽  
Asymmetric Catalysis ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
High Surface Area ◽  
Metal Organic

Homochiral metal–organic frameworks (HMOFs) are attractive materials for asymmetric catalysis because they possess high surface area and uniform active sites.

scholarly journals Outstanding fuel cell performance of a fully platinum-free electrocatalysts using a cost-effective catalyst support material

2020 ◽  
Author(s):  
Priji Chandran ◽  
Sundara Ramaprabhu
Keyword(s):  
Fuel Cell ◽  
Surface Area ◽  
Power Density ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Cost Effective ◽  
Support Material ◽  
Carbon Nanostructure ◽  
Tubular Morphology

One of the effective ways to increase the electrocatalytic activity of carbon based electrocatalyst in a fuel cell is by in-situ incorporation of heteroatom into the carbon nanostructure. Herein, a cost effective catalyst support material, nitrogen rich carbon nanostructure (NCNS) with high surface area and tubular morphology was synthesized. NCNS supported palladium-alloy based electrocatalyst (Pd3Co/NCNS) was successfully prepared and used on both sides of a fuel cell as potential alternative to expensive Pt-based electrocatalysts. The large number of nitrogen-carbon moieties present in NCNS served as anchoring sites for catalyst nanoparticles. Moreover, the tubular morphology and high surface area plays an important role in enhanced electrochemical activity of the prepared nanocomposite. The Pd-based bimetallic alloy dispersed on NCNS exhibited high activity towards both oxidation of hydrogen and reduction of oxygen in acidic medium. Thus, a fully Pt-free electrocatalyst was constructed using a cost effective electrocatalyst. The peak power density achieved using Pd3Co/NCNS at both anode and cathode simultaneously was found to be almost 25 % of the maximum power density attained using commercial Pt/C on both sides, which is the maximum value reported so far in PEMFC without using Pt on either side.

Novel Xerogel Catalyst Materials for Hydrogenation Reactions and the Role of Atomic Scale Interfaces

1999 ◽  
Vol 5 (S2) ◽  
pp. 704-705
Author(s):  
P.L. Gai ◽  
K. Kourtakis ◽  
H. Dindi ◽  
S. Ziemecki
Keyword(s):  
High Resolution ◽  
Active Sites ◽  
Heterogeneous Catalysts ◽  
Low Voltage ◽  
High Surface ◽  
Sol Gel ◽  
High Surface Area ◽  
High Resolution Electron Microscopy ◽  
Atomic Scale ◽  
Hydrogenation Reactions

We are developing a new family of heterogeneous catalysts for hydrogenation catalysis. Catalyst synthesis is accomplished using colloidal polymerization chemistry which produce high surface area xerogel catalysts. These xerogels have been synthesized by one-step sol gel chemistry. These catalysts contain ruthenium and modifiers such as gold occluded or incorporated in a titanium oxide matrix. The materials, especially the modified systems exhibit favorable performance in microreactor evaluations for hydrogenation reactions and exhibit high activities. Nanostructural studies have revealed that the materials contain dispersed catalyst clusters which are desirable microstructures for the catalysis since the majority of the atoms are exposed to catalysis and are potentially active sites.The composition and atomic structure of the xerogel catalysts containing ruthenium and other metals have been examined using our in-house developments of environmental high resolution electron microscopy (EHREM) the atomic scale [1-3] and low voltage high resolution SEM (LVSEM)[4] methods.

Bimetallic Basic Catalyst Comprising Niobium and Cesium Supported on MCM-48 for the Claisen-Schmidt Condensation

2012 ◽  
Vol 545 ◽  
pp. 379-384
Author(s):  
Salasiah Binti Endud ◽  
Nadirah Zawani Binti Mohd Nesfu
Keyword(s):  
Mesoporous Silica ◽  
Active Sites ◽  
Aldol Condensation ◽  
High Surface ◽  
Catalyst Support ◽  
High Surface Area ◽  
Antibacterial Activities ◽  
Catalyst Stability ◽  
High Concentration ◽  
Carbon Carbon Bond

The Claisen–Schmidt condensations stand out to be important reaction in carbon–carbon bond formation as well as in the preparation of fine chemicals and intermediates with the presence of base catalyst such as NaOH. However, only few studies concern the synthesis and catalytic activity of mesoporous silica containing bimetallic compound as catalyst for aldol condensation of bulky aldehydes. The advantages of mesoporous systems with respect to zeolites are the improved reactant accessibility to the active sites and enhanced catalyst stability. Mesoporous silica with exceedingly high surface area (> 800 m2/g) and very high concentration of surface silanol groups fulfill most of the criteria for catalyst support. In this contribution, we report on the incorporation of Nb and Cs, alone or together, into the mesoporous silica with cubic mesostructure and the investigation of their catalytic properties in the Claisen-Schmidt condensation of acetophenone with benzaldehyde to produce chalcone, an aromatic ketone that forms the active sites for important biological compounds with antibacterial activities.

Electron holography of catalysts

1995 ◽  
Vol 53 ◽  
pp. 416-417
Author(s):  
A. K. Datye ◽  
D. S. Kalakkad ◽  
L. F. Allard ◽  
E. Völkl
Keyword(s):  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Atomic Scale ◽  
Nano Particles ◽  
Phase Image ◽  
Electron Holography ◽  
Specimen Thickness ◽  
Phase Information ◽  
Particle Structure

The active phase in heterogeneous catalysts consists of nanometer-sized metal or oxide particles dispersed within the tortuous pore structure of a high surface area matrix. Such catalysts are extensively used for controlling emissions from automobile exhausts or in industrial processes such as the refining of crude oil to produce gasoline. The morphology of these nano-particles is of great interest to catalytic chemists since it affects the activity and selectivity for a class of reactions known as structure-sensitive reactions. In this paper, we describe some of the challenges in the study of heterogeneous catalysts, and provide examples of how electron holography can help in extracting details of particle structure and morphology on an atomic scale.Conventional high-resolution TEM imaging methods permit the image intensity to be recorded, but the phase information in the complex image wave is lost. However, it is the phase information which is sensitive at the atomic scale to changes in specimen thickness and composition, and thus analysis of the phase image can yield important information on morphological details at the nanometer level.

Metal-organic-framework derived hollow manganese nickel selenide spheres confined with nanosheets on nickel foam for hybrid supercapacitors

2021 ◽  
Author(s):  
Bahareh ameri ◽  
Akbar Mohammadi Zardkhoshoui ◽  
Saied Saeed Hosseiny Davarani
Keyword(s):  
Active Sites ◽  
Nickel Foam ◽  
Metal Organic Framework ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
High Surface Area ◽  
Supercapacitive Performance ◽  
Hybrid Supercapacitors ◽  
Porous Networks ◽  
Metal Organic

Metal-organic frameworks (MOFs) derived nanoarchitectures have special features, such as high surface area (SA), abundant active sites, exclusive porous networks, and remarkable supercapacitive performance when compared to traditional nanoarchitectures. Herein,...

scholarly journals Cobalt-Based Metal Organic Frameworks as Solids Catalysts for Oxidation Reactions

Catalysts ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 95
Author(s):  
Amarajothi Dhakshinamoorthy ◽  
Eva Montero Lanzuela ◽  
Sergio Navalon ◽  
Hermenegildo Garcia
Keyword(s):  
Aerobic Oxidation ◽  
High Surface ◽  
Metal Organic Frameworks ◽  
High Surface Area ◽  
Acid Sites ◽  
Crystalline Lattice ◽  
Oxidation Reactions ◽  
Solid Catalysts ◽  
Long Term Stability ◽  
Metal Organic

Metal organic frameworks (MOFs) are porous crystalline solids whose frameworks are constituted by metal ions/nodes with rigid organic linkers leading to the formation of materials having high surface area and pore volume. One of the unique features of MOFs is the presence of coordinatively unsaturated metal sites in their crystalline lattice that can act as Lewis acid sites promoting organic transformations, including aerobic oxidation reactions of various substrates such as hydrocarbons, alcohols, and sulfides. This review article summarizes the existing Co-based MOFs for oxidation reactions organized according to the nature of substrates like hydrocarbon, alcohol, olefin, and water. Both aerobic conditions and peroxide oxidants are discussed. Emphasis is placed on comparing the advantages of using MOFs as solid catalysts with respect to homogeneous salts in terms of product selectivity and long-term stability. The final section provides our view on future developments in this field.

Studies of Supported Metal Catalysts Using Low Voltage Biased Secondary Electron Imaging in a JSM-6320f Fe-SEM

1997 ◽  
Vol 3 (S2) ◽  
pp. 1223-1224
Author(s):  
J. Liu ◽  
R. L. Ornberg ◽  
J. R. Ebner
Keyword(s):  
Secondary Electron ◽  
Low Voltage ◽  
Supported Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Incident Beam ◽  
Active Species ◽  
Supported Metal Catalysts ◽  
Active Components ◽  
Electron Imaging

Many industrial catalysts have a complex geometric structure to enable reacting gases or fluids to reach as much of the active surface of the catalyst as possible. The catalyzing surface frequently consists of a complex chemical mixture of different phases produced by an evolved chemical process. The active components are often very small particles dispersed on high-surface-area supports. The catalytic properties of this type of catalyst depend on the structure, composition, and morphology of the active species as well as the supports. TEM/STEM and associated techniques have been used extensively to characterize the structure and composition of supported catalysts. Surface morphology of supported catalysts is generally examined by secondary electron imaging, especially at low incident beam energies. It is, however, frequently found that small metal particles are not usually seen in SE images because of the complication of support topography

Spidery catalyst for the synthesis of quinazoline-2,4(1H,3H)-diones

2016 ◽  
Vol 6 (5) ◽  
pp. 1435-1441 ◽  
Author(s):  
Seyed Mohsen Sadeghzadeh
Keyword(s):  
Surface Area ◽  
Active Sites ◽  
High Surface ◽  
High Surface Area

In this study, a novel fibrous nanosilica (KCC-1) based nanocatalyst (Au, Pd, and Cu) with a high surface area and easy accessibility of active sites was successfully developed by a facile approach.

Metal nanoparticles: ligand free approach towards coupling reactions

2021 ◽  
Vol 01 ◽  
Author(s):  
Sharwari K. Mengane ◽  
Ronghui Wu ◽  
Liyun Ma ◽  
Chhaya S. Panse ◽  
Shailesh N. Vajekar ◽  
...  
Keyword(s):  
Heterogeneous Catalysis ◽  
Metal Nanoparticles ◽  
Surface Area ◽  
Heterogeneous Catalysts ◽  
High Surface ◽  
High Surface Area ◽  
Reaction Medium ◽  
Coupling Reactions ◽  
Research Activities ◽  
Ligand Free

: Catalysis is the multidisciplinary field involving many areas of chemistry, notably in organometallic chemistry and materials science. It has great applications in synthesis of many industrially applicable compounds such as fuels and fine chemicals. The activity and selectivity are a key issue in catalysis that generally allied to high surface area. The current research activities mainly deal with the homogeneous and heterogeneous catalysis. Homogeneous and heterogeneous catalysis have certain drawbacks which restricts their application to great extent but have their own advantages. Hence, it has a predominant concern of current research to find out an alternate to overcome their drawbacks. Therefore, it is highly desirable to find a catalytic protocol that offers high selectivity and excellent product yield with quick and easy recovery. Along with their various applications as alternatives to conventional bulk materials nanomaterial have established its great role in different industrial and scientific applications. Nanocatalysis has emerged as new alternative to the conventional homogeneous and heterogeneous catalysis. The nanomaterials are responsible to enhance surface area of the catalyst, which ultimately increases the catalyst reactants contacts. In addition, it acts as robust material and has high surface area like heterogeneous catalysts. Insolubility of such nanomaterial in reaction medium makes them easily separable, hence, catalyst can be easily separate from the product. Hence, it has been proven that nanocatalysts behave like homogeneous as well as heterogeneous catalysts which work as a bridge between the conventional catalytic systems. Considering these merits; researchers has paid their attention towards applications of nanocatalyst in several organic reactions. This review article focused on the catalytic applications of metal nanoparticles (MNPs) such as Pd, Ag, Au, Cu, Pt in ligand free coupling reactions. In addition, it covers applications of bimetallic and multimetallic nanoparticles in ligand free coupling reactions.

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